ORIGINAL ARTICLE
UROPATHOGENS AND THEIR ANTIMICROBIAL SUSCEPTIBILITY
PATTERN IN A TERTIARY CARE HOSPITAL
Yashavanth R, Ronald R, Anita K, Narendra N, Faseela T
1.
2.
3.
4.
5.
Assistant Professor, Department of Microbiology, AJIMS, Kuntikana, Bejai, Mangalore.
Professor and HOD, Department of Microbiology, AJIMS, Kuntikana, Bejai, Mangalore.
Associate Professor, Department of Microbiology, AJIMS, Kuntikana, Bejai, Mangalore.
Professor, Department of Microbiology, AJIMS, Kuntikana, Bejai, Mangalore.
Lecturer, Department of Microbiology, AJIMS, Kuntikana, Bejai, Mangalore.
CORRESPONDING AUTHOR
Dr. Yashavanth Kumar Rai,
Assistant Professor, Dept Microbiology,
AJIMS, Mangalore,
E-mail: dryashwanthrai@gmail.com,
Ph: 0091 9986297656.
ABSTRACT: BACKGROUND: Urinary tract infections (UTI) are one of the most common
infectious diseases in humans. Antimicrobial drug resistance is one of the major threats due to
wide spread use of inappropriate and empirical antibiotic therapy. The present study highlights
the organisms causing UTI and their antimicrobial susceptibility pattern. MATERIALS AND
METHODS: A total number of 1266 urine samples were analysed in a tertiary care hospital.
Urine samples were processed by calibrated loop technique, delivering 0.001 ml of urine and
plated on to MacConkey’s and Cysteine Lactose Electrolyte Deficient (CLED) agar plates and
incubated at 370C overnight. Appropriate biochemical tests were carried out to identify the
uropathogens. Antimicrobial susceptibility of the isolates was determined against various
antimicrobial agents. RESULTS: Among this, 332(26.22%) culture positive isolates were
identified and their antimicrobial susceptibility patterns were analysed. Among the culture
positive isolates, Escherichia coli (54.21%)was the most common pathogen followed by
Klebsiella spp (22.89%) and Enterococcus spp (6.92%). Majority of these isolates were
resistant to Cotrimoxazole, Amoxycillin/ Clavulanic acid, Piperacillin, Norfloxacin, Ciprofloxacin
and also to third generation cephalosporins. Escherichia coli isolates showed good sensitivity
towards Amikacin, Piperacillin/ Tazobactum, Nitrofurantoin and Meropenem. Klebsiella isolates
showed good sensitivity towards Amikacin, Levofloxacin, Piperacillin/ Tazobactum and
Meropenem. Staphylococcus aureus and Enterococcus spp showed good response towards
Linezolid, Netilmicin, Vancomycin and Teicoplanin. There is also increase in incidence of
Extended Spectrum Beta Lactamase (ESBL) production among Escherichia coli (65%) and
Klebsiella spp (55%). Study also showed that females (67.17%) are more vulnerable to urinary
tract infections than males (32.83%). CONCLUSION: Due to excessive use of antimicrobials for
all sorts of infections, uropathogens are increasingly showing resistance to antibiotics.
Knowledge of uropathogens and their antimicrobial susceptibility pattern in a geographical
region will help in appropriate and judicious antibiotic usage in a health care setup.
KEYWORDS: Urinary Tract Infection, Antibiotic Susceptibility Pattern, ESBL
INTRODUCTION: Urinary tract infections (UTI) are one of the most common infectious diseases
in humans. Antimicrobial drug resistance is one of the major global threats.1Antibiotics are
usually given empirically before the laboratory reports of urine cultures are available.
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ORIGINAL ARTICLE
Inappropriate and empirical usage of wide spectrum of antibiotics, insufficient hygiene,
immunosuppression and prolonged hospitalisation are some of the major etiological factors
that increase the chances of UTIs.2Wide spectrum of organisms are implicated in its aetiology,
the most common being Escherichia coli and Klebsiella spp followed by Gram positive
organisms.3
Gram negative bacilli shows high incidence of resistance against Cotrimoxazole,
Norfloxacin, Piperacillin, Fluoroquinolones and third generation cephalosporins.4,5Gram
positive cocci shows high incidence of resistance against Ampicillin, Amoxycillin, Penicillin,
Amoxycillin/ Clavulanic acid and Erythromycin. Antibiotic susceptibility pattern of
uropathogens vary according to the geographical and regional locations. The knowledge about
uropathogens and their resistance patterns is important for appropriate therapy and also for
prevention of resistance amongst the microbes. In this context present study was carried out to
know the common uropathogens and their susceptibility pattern in a tertiary care hospital.
MATERIALS AND METHODS: A total of 1266 clean catch midstream urine samples were
collected in a sterile container from both outpatients and inpatients in our hospital during study
period (January 2010 – December 2011). Urine samples were transported immediately to
microbiology laboratory and processed. Urine samples were processed by calibrated loop
technique delivering 0.001 ml of urine and plated on to MacConkey’s and Cysteine Lactose
Electrolyte Deficient (CLED) agar plates and incubated at 370C overnight. For Gram negative
bacilli more than 105 colonies per ml and for Gram positive cocci 103-105 colonies per ml of
single organism were considered significant. Uropathogens were further identified by the
morphological and biochemical characteristics.6
Antimicrobial susceptibility of the isolates was determined against various antimicrobial
agents by Kirby Bauer disk diffusion method on Muller Hinton agar plates according to Clinical
and Laboratory Standard Institute(CLSI) guidelines.7Antibiotics for Gram negative bacilli
included Amikacin(AK-30μg), Ceftazidime (Ca- 30 μg), Cefotaxime (Ce-30μg), Ceftriaxone (Ci30 μg), Cefepime (Cpm- 30μg), Ciprofloxacin (Cf- 5μg), Cotrimoxazole (Co-25μg), Gentamycin (G
-10μg), Levofloxacin(Le-5μg), Piperacillin(Pc-100μg), Piperacillin- Tazobactum(Pt- 100/10μg),
Norfloxacin ( Nx -10μg), Nitrofurantoin ( Nf - 300μg), Ofloxacin (Of - 5μg), Meropenem (Mr10μg), Aztreonam (Ao-30μg). Escherichia coli and Klebsiella isolates were tested for Extended
Spectrum Beta Lactamase (ESBL) production by double disk diffusion method with Ceftazidime
and Ceftazidime Clavulanic acid combination as recommended by CLSI guidelines.7, 8Escherichia
coli ATCC 25922 and Klebsiella pneumoniae ATCC 700603 strains were used as controls.
Gram positive cocci were tested for Ampicillin (A-10μg), Amoxycillin (Am -30 μg),
Cephoxitin (Cn-30μg), Clindamycin (Cd-2μg), Erythromycin (E-15μg), Linezolid (Lz -30μg),
Netilmicin (Nt -30μg), Penicillin (P-10 units), Teicoplanin (Te-30μg), Vancomycin (Va-30 μg) (Hi
Media, Mumbai). Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212
strains were used as controls. The results were recorded and interpreted according to CLSI
guidelines.
RESULTS: Out of 1266 urine samples, 332(26.22%) were found to be culture positive isolates.
Among 332 culture positive isolates, 223 (67.17%) were obtained from females and
109(32.83%) were obtained from males as shown in Table1. The highest isolation rates was
found in 20 – 69 age group as shown in Table 2.
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ORIGINAL ARTICLE
Escherichia coli(54.21%) was the predominant uropathogen, followed by Klebsiella
spp(22.89%), Enterococcus spp(6.92%), Staphylococcus aureus (5.21%), Acinetobacter spp
(3.31%) and Citrobacter spp (3.01%) as shown in Table 3. The antibiotic resistance among
uropathogens to the agents that had been recommended as the first line therapy is on rise. The
Gram negative bacilli which were isolated showed high degree resistance pattern against
Cotrimoxazole, Norfloxacin, Piperacillin, Ciprofloxacin and third generation cephalosporins.
Escherichia coli isolates showed higher sensitivity towards Amikacin (91.18%), Nitrofurantoin
(90.52%), Piperacillin- Tazobactum (96.44%) and Meropenem (100%). Klebsiella isolates
showed good response towards Amikacin (92.61%), Levofloxacin (90%), PiperacillinTazobactum (95%), Meropenem (100%) as shown in Table 4. ESBL production among
Escherichia coli isolates were 65% and Klebsiella isolates, 55%. Enterococcus spp showed good
response towards Linezolid (100%), Vancomycin (100%), and Teicoplanin (87.5%).
Staphylococcus aureus showed good response towards Linezolid (88.1%), Netilmicin (87.5%),
Vancomycin (100%), Teicoplanin (100%), as shown in Table 5.
DISCUSSION: The changing trends in the aetiopathogenesis of urinary tract infections and
increasing antimicrobial drug resistance are a matter of concern. Urethral catheterisation and
instrumentation related UTI is the most common nosocomial infection.9 Catheter related UTI
increases morbidity, mortality and also cost of treatment for patients in a health care setup. 10
The indiscriminate, inadequate usage of antibiotics has contributed to the emergence of
resistance strains.11Urine culture sensitivity is routinely done in suspected cases of UTI and
empirical therapy should be started immediately and modified if required once the report of
urine culture sensitivity is available.12, 13
The present study shows the pathogens causing UTIs and their antibiotic susceptibility
pattern. Escherichia coli was the predominant pathogen followed by Klebsiella spp and Gram
positive cocci. This study is in concordance with the studies done by Manjunath et al,1 and
Shigemura et al. 7 Our study shows that females (67.17%) are more vulnerable to UTIs than
males (32.83%), which is similar to previous studies done by Manjunath et al,1and Dash et al.14
Females are more prone to UTIs probably due to their short urethra and physiological changes.
Antimicrobial resistance of different uropathogens is one of the barricades that can interfere
with an effective treatment. The present study indicates different antimicrobial susceptibility
pattern among uropathogens. The broad spectrum activity of Fluoroquinolones and third
generation Cephalosporin has made them therapeutic options for UTIs. The organisms which
belonged to Enterobacteriaceae family, showed high degree of resistance towards
Cotrimoxazole, Fluoroquinolones and third generation Cephalosporin, but these isolates
showed good response against antibiotics like Amikacin, Nitrofurantoin, Piperacillin
Tazobactum and Meropenem. This finding is similar to the studies done by Manjunath et al, 1and
Shigemura et al.7 Our study also shows increase in ESBL producing strains among Escherichia
coli (65%) and Klebsiella spp (55%), which is similar to the results of the studies done by Shiju
et al,8and Shukla et al.15 ESBL producing organisms pose a major problem in clinical
therapeutics, so there is a need for judicious use of antimicrobial agents and their continuous
Invitro monitoring should be carried out, so that misuse of extended spectrum cephalosporins
can be avoided. Gram positive cocci showed good susceptibility patterns towards Netilmicin,
Linezolid, Vancomycin and Teicoplanin.
This study furnishes the much needed information on the common uropathogens and
their antibiotic susceptibility pattern in our region. In view of the emerging drug resistance
Journal of Evolution of Medical and Dental Sciences/Volume1/ Issue4/October - 2012 Page 469
ORIGINAL ARTICLE
among uropathogens, therapy should be commenced after the culture and sensitivity has been
performed. This would, not only help in the proper use of antibiotics but also prevent further
development of bacterial drug resistance in community as well as in hospitals.
Table 1: Sex- wise distribution of UTI
GENDER
Number of Isolates
Male
Female
109(32.83%)
223(67.17%)
Table 2: Age-wise distributions of uropathogens
Age group
Male
Female
Total
0-9
3
18
21
10-19
10
35
45
20-29
15
58
73
30-39
16
36
52
40-49
23
23
46
50-59
13
23
36
60-69
23
20
43
70-79
3
8
11
80-89
3
2
5
Table 3: Clinical strains isolated from urine samples.
Uropathogens
Escherichia coli
180
No. of isolates
54.21%
Percentage
Klebsiella spp
76
22.89%
Acinetobacter spp
11
3.31%
Citrobacter spp
10
3.01%
Pseudomonas spp
8
2.40%
Provedencia spp
4
1.20%
Proteus mirabilis
2
0.60%
Enterobacter spp
`
Enterococcus spp
1
0.30%
23
6.92%
Staphylococcus aureus
17
5.12%
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ORIGINAL ARTICLE
Table 4: Antibiotic Susceptibility pattern(% sensitivity): Gram negative bacilli.
Uropa
thogen
Ak
Ao
Ca
Ce
Ci
Cpm
Cf
Co
G
Le
Mr
Nx
Nf
Of
Pc
Pt
E.coli
91.18
ND
36.99
33.38
32.34
35.88
31.20
28.31
58.67
60.9
4
100
23.7
7
90.5
2
53.47
23.
74
96.44
Klebsi
ella
Spp
92.61
ND
46.89
39.64
41.3
49.51
53.75
49.61
68.35
90
100
50.6
9
70
43.18
29.
11
95
Acinet
obacte
r
spp
83.33
ND
71.42
66.66
66.66
ND
66.66
50
70
100
81.81
75
ND
50
50
81.81
Citrob
acter
Spp
79.16
ND
65
45
66.66
40
79.16
55
73.33
75
100
60
70.8
70
40
87.5
Proteu
s
Spp
100
ND
50
50
50
50
50
50
ND
100
100
50
100
50
ND
100
Pseud
omona
s
Spp
50
37.
5
50
50
37.5
ND
37.5
37.5
ND
50
75
50
ND
37.5
62.
5
87.5
Provid
encia
Spp
100
ND
50
50
50
ND
50
25
ND
75
100
50
75
50
50
100
Entero
bacter
spp
100
ND
-
-
-
ND
-
-
ND
100
100
-
100
-
-
100
Table5: Antibiotic Susceptibility pattern(% sensitivity): Gram positive cocci
A
S.aureus
25
Am
Ac
Cd
Cz
Cn
E
G
Lz
Nt
Nx
Nf
P
Va
29.16 50 70.1 53.5 53.57 52.94 63.85 88.1 87.5 ND ND 11.8 100
Enterococcus 14.28
20
Spp.
*ND-NOT DONE.
36 ND
ND
ND
36
46.66 100
ND
40
60
20
100
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Journal of Evolution of Medical and Dental Sciences/Volume1/ Issue4/October - 2012 Page 471
Te
100
87.5
ORIGINAL ARTICLE
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